“Stop the Presses!” is a term you really only understand once you have seen these gigantic machines churn out sheet after sheet in rapid succession. They do seem almost unstoppable. Yet here they fell silent again, after just a few sheets had been printed. It was time for the press check. We were at our printer, meeting with the press manager to make sure the printed sheets match the vibrancy of our proofs. This is where our vision for Bicycle Quarterly becomes reality.

The press manager pulls a few sheets off the press. We compare those sheets to the proofs and tell the manager what we envision. The scanner (shown above) determines the amount of pigment actually put down by the press. The press manager adjusts the color balances and intensities to obtain the most vibrant, life-like image quality. Then the gigantic press starts up again and spits out a few pages with the new settings.

As I see the photos come off the press, I think back to when we were out riding and scouting for photo locations. Back then, I was trying to envision how the shot would look on the printed page. And now that printed page is coming off the press! It’s been a long process to get to this final, vital step in making it all come together.

This time, it seemed to us that the printed sheets looked even better than before. When asked, the press manager told us they started using a new ink with a higher pigment load, which allowed them to push their press settings a little further. He was visibly proud of this change. Once you’ll hold the Spring issue in your hands, I think you’ll agree with him – the new issue looks even better than the previous ones.

I went cross-country skiing with my family last week. I hadn’t skied in more than a decade, and I never had skate-skied before. It looked like fun, so I rented skis and took a one-hour introductory lesson. Then I headed out on the trails.

I was looking forward to gliding through the snow like I knew from classic Nordic skiing, yet I was very surprised how much fun skate-skiing is. The gently rolling trail followed a creek along the edge of the hills. Even though the water was flowing toward me, I felt like I was going downhill! When I turned around, I really was going downhill, which was even more fun.

Skate-skiing really was exhilarating – it felt like being on a bike that planes perfectly, with none of the push-back you sometimes get when you try to pedal harder. On skate skis, you don’t push off, but just step forward with your feet at an outward angle, and then your legs just go. Every second step, you use your poles to balance and get a little extra propulsion. As I skated through the sparse forest, speed built quickly. I was breathing hard and enjoying the “taste of the effort”, but it seemed effortless. And I covered a lot of ground quickly. I wasn’t the only one enjoying it: A woman and daughter came flying toward me, their arms waving from side to side beautifully in sync with their strides. Their smiles were as big as mine.

It was fun to be out in the mountains, too. I’ve cycled through these places in summer, but it was very different now. The quality of light, reflected by the snow from all sides, was so much more luminous. We have very little snow pack in the Cascades this winter, sadly, as you can see on the hills; definitely too light for February. However, there was still enough snow on the trails to ski.

The next three days were pure bliss. Every morning, I rose before sunrise, and headed out on the trails. I explored new trails every day, including one on the last day that had a wonderful flow of ups and downs. On the downhills, I learned to step around corners, rather than snowplow and lose speed. Approaching the limits of my skills and capabilities was exhilarating, and it was good to know that if things got out of hand, I could just sit down and stop on my behind (which I did do once.)

The snowplowing for tighter turns was fun, too, since you adjust your arc by weighing the outer or inner skis. The skis are aligned in a triangle. Weighing the outer ski pulls you into the turn, weighing the inner ski widens your arc. It reminded me a lot of riding on gravel or mud, where you play with the traction of your bike’s tires. But here, it’s easier because you don’t face a sudden loss of traction – you are always sliding and working with it.

I expected to be sore from so much skiing, like I used to be after classic cross-country skiing. However, it seems that skating uses similar muscles as cycling, and only my hands got a little tired from gripping the poles.

If you live in a place where snow prevents you from cycling, now I envy you! I now dream of having a groomed trail behind my house, so I could ski for an hour or two every morning…

Over the last decade-and-a-half, I’ve thought a lot about product development. Long before Bicycle Quarterly and Compass Bicycles, I was involved with several companies as a technical writer and translator. Part of my job was writing instructions, so I got to see product development up close.

From my experience, product development ideally has three components:

Skilled users who are sensitive enough to report what they experience.

Scientists who design tests to confirm those observations and isolate the factors involved.

Engineers who translate those findings into better products.

With Bicycle Quarterly, it didn’t take long until we got involved in No. 1. We rode many bikes over challenging courses, and we noticed differences in how they performed, how they handled, and how they felt.

From those observations, it was a small step to No. 2. After all, our editorial team is made up of scientists, so the question “Why do some bikes ride/perform/handle better than others?” came up quickly. We began testing tires, we tested our hypotheses about frame stiffness, and we rode different front-end geometries.

No. 3 was a logical next step – what good are scientific findings if they don’t lead to bicycles people can ride? So we started Compass Bicycles to translate the results of our research into better bicycle components.

Sometimes, steps 1 and 2 are reversed. That is how our tires came about. I hadn’t thought much about tires, until I saw a tire test in the German magazine TOUR. (By the way, the title in the photo above translates to “Roll Well”.)

Among other things, TOUR tested the tires’ rolling resistance. They found significant differences, but downplayed them by saying that the difference would “only” amount to 138 seconds in a 40 km time trial. That got me thinking: First of all, more than 2 minutes in a time trial is a huge difference. When I raced, 10 seconds over 10 km made the difference between first and fifth place. Could the faster tires have made me a consistent winner? More importantly, speeds are lower for the long rides we now enjoy, so rolling resistance is even more important.

Talking with Mark Vande Kamp (friend, riding companion and fellow Ph.D. on Bicycle Quarterly‘s editorial board), we decided to see whether we could replicate TOUR‘s results, but at lower speeds. We bought a set each of the fastest tire in the TOUR test, as well as a slower one. We scouted a location for a rolldown test, and one Saturday morning, we installed the test tires on our bikes and headed to the hill. I rolled downhill, first on one tire, then on the other (always using the same bike, of course). Mark timed me and found that the differences were quite large: about 10% faster with one tire than the other. We repeated the experiment, and the results were the same. Wow! Tires did make a larger difference than we thought. We knew we had to test this further.

We then went on a long ride and discussed what we wanted to test. Different tire models, obviously, but also different pressures. After all, we always were torn between inflating our tires to the maximum pressure to obtain the highest speed, and reducing the pressure a little to improve comfort. How much speed did we lose if we went for comfort? We also decided to test the same tires in different widths. And worn tires against new ones, to determine how much of a difference tread thickness makes. (Worn tires have a thinner tread, but otherwise are the same as new ones.)

The testing took a lot of time and effort, but the results were worth everything we put into it. We found out that the tires I had been using were among the slowest tires in our test. Simply replacing my tires allowed me to stay with previously faster riders during brevets. And when I rode alone, I consistently set personal bests, despite my training being the same as before.

As a positive side effect, the faster tires also were more comfortable. However, comfort was relative: The fastest tires in our test were only 24 mm wide – too narrow for true comfort on backroads.

Our research showed ways to improve these tires. We found that tire pressure did not have a significant effect on speed. This opened up a whole new way forward for tire design. Instead of trying to make wider tires withstand high pressures (which requires strong, stiff casings), wider tires should be made supple casings. Despite running at lower pressures, they’d be much faster.

At the time of our tire tests, we just had started to sell the first-generation Grand Bois tires (above). We were disappointed that they did not score well in our tests. We shared our results with Grand Bois and Panaracer, and they came up with an improved version that had a more supple casing. That was the first product that came directly out of Bicycle Quarterly‘s testing.

Over the next few years, the Grand Bois tire program expanded, and we were able to test our findings on the road. We found that even with 42 mm-wide tires, our bikes were no slower than bikes with narrower tires. And Grand Bois worked with Panaracer to further improve the casings, resulting in the Extra Léger models.

We felt that further improvements were possible by optimizing the tire tread for performance. The tread on the shoulders of the tire only contacts the road during hard cornering, so it doesn’t wear out. We could make this thinner, so the tires would be even more supple and faster. We tested many tread patterns to obtain an optimum of cornering traction both on dry and wet roads. The result were our Compass tires. Our customers rave about their comfort, speed, cornering grip…

Our tires are just one example of the symbiotic relationship between Bicycle Quarterly and Compass Bicycles. Without Bicycle Quarterly‘s research, we wouldn’t have known that the tires we were using were slow. And without Compass Bicycles, our research would have remained of little use to riders. We would have outlined “ideal” performance tires, but without anybody making them, that knowledge would not have improved our riding experience.

The main reason Compass components exist is so we can use them on our own bikes! And I truly believe that our riding experience has improved in many ways since we starting riding on wide, supple tires.

A little while ago, I wrote about how new scientific research has allowed us to design wide, supple tires that offer the speed of narrow, high-end racing tires. The key finding is that above a certain threshold, increasing tire pressure no longer results in lower rolling resistance. While these new data have become widely accepted – witness professional racers adopting wider tires and lower pressures – it’s natural that new ideas are met with skepticism. In order to contribute to a better understanding of how tires work, I’d like to share more data from Bicycle Quarterly‘s testing.

The data above came from Bicycle Quarterly rolldown tests of various tires. The results indicate that above a certain threshold, for clinchers, tire performance increases only very slightly, if at all. It’s not surprising that the 38 mm-wide Mitsuboshi tire rolled faster at 35 psi than at 25 psi – it was hardly rideable at the lower pressure. But increasing pressure to 55 psi resulted in no speed increase.

We saw the same for the 27 mm-wide Rolly-Poly. Somewhere between 55 and 85 psi, higher pressure no longer resulted in significantly increased performance. Going from 85 to 105 psi resulted in only a minimal increase in speed. For the two tubular tires, the effect was reversed: Higher pressures actually reduced performance.

We’ve confirmed this finding numerous times. Above is another set of test runs (pressures are in bar/psi). For these 32 mm tires, increasing the pressure from 7o psi to 85 psi brought no significant change in performance. (The apparently slower speed at 85 psi is not statistically significant.) Please note that the values you see here are not corrected for temperature, so you can’t compare different tires. (The pressure runs were done consecutively, so temperature didn’t change from one pressure to the next.)

We discussed the measurements with power meters in the previous post (above). That data also has been confirmed multiple times, at different speeds.

Above is data from running ultra-high pressures, up to 200 psi. Performance did not change with increasing pressures. (Don’t do this at home, 14 bar/200 psi is not safe with these tires!) I could bore you with even more data, but I think this is pretty convincing, especially since we’ve confirmed numerous times that our tests are repeatable (testing the same setup multiple times yields the same results) and statistically significant (meaning we aren’t just looking at random noise in the data). That is important, because all too many studies are based on single test runs, which don’t meet basic scientific requirements. Now that we’ve conclusively debunked the old view of “higher pressure = more speed”, let’s look at some of the details in the data above.

Rough vs. Smooth Pavement

The rolldown tests were performed on relatively rough pavement. No holes or bumps, but the tar between the aggregate had washed away over decades of Seattle weather. Interestingly, high pressures generally did result in slightly higher speeds for some clincher tires. It’s not a lot, but it’s statistically significant.

The track tests were run on very smooth, newly laid asphalt pavement. There, we see the opposite. High pressures of 100-110 psi result in slightly lower speeds. How can we explain this? One hypothesis is that the tire deforms more on the rougher pavement to conform to the surface irregularities. At lower pressure, you create an imprint of the road surface in the tire as it rolls. At higher pressure, the tire bridges the gaps between the high points, and thus deforms less. On the smooth road, there aren’t any gaps to bridge, and so the high pressure loses its advantage.

Moderately high pressure = worst performance

On the smooth track, moderately-high pressure (100-110 psi) is worse than either lower or higher pressures. Why is that? Here is a possible explanation: As you increase the pressure, the suspension losses (vibrations) increase faster than the flexing of the tire (hysteresis) is reduced. So you lose performance as you increase pressure. At a certain point, the bike is vibrating as much as it can, but higher pressures still reduce the flexing of the tire. So from that point onward, higher pressures improve performance – until you end up back where you started at lower pressures.

Tubulars vs. Clinchers

What about the worse performance of tubulars at higher pressures? Tubulars derive much of their performance from their suppleness and low suspension losses. Increasing the pressure increases vibrations faster than it reduces the flexing of the tires. These explanations are just hypotheses – our best guesses to explain what we see. The data itself – higher pressures don’t lead to improved performance – is beyond doubt.

Take-Home Message

For most riders, the take-home message is simply this: As long as you inflate your tires enough that they are safe to ride, tire pressure doesn’t matter much. Find a pressure that feels good when cornering, and ride your tires at that pressure. When in doubt, let out some air – you’ll be more comfortable and have better cornering grip. (If you ride narrow tires, beware of pinch flats, though!)

If you worry about the last bit of performance, then you can try to use the data above to tease out that last 2%. On smooth roads, low tire pressures yield the best performance. On rough pavement that doesn’t have holes or bumps, increasing your pressure may make your tires a little bit faster. That may seem counter-intuitive, and of course, it also will be less comfortable. But if you are doing a short time trial on a country road, it may be worth considering. Ideally, you’d run a few experiments with a power meter to dial in your tire pressure for that particular road surface.

If you run tubular tires, you should definitely run them at relatively low pressures. This provides the best performance and the best comfort on all surfaces we’ve tested. As for me, I run my tires at relatively low pressures on all roads. My rides encompass a multitude of surfaces, and on truly bumpy roads, we’ve shown that lower pressures always are faster, because the bike bounces less. But that is a topic for another day…

If you have been around randonneurs lately, you’ll have noticed a buzz around three letters: PBP. The 1200 km ride from Paris to Brest and back has captured the imagination of cyclists for more than a century. It’s now organized every four years, and 2015 is one of those years!

Randonneurs sometimes have a hard time communicating why they love this ride. They tend to focus on the easy-to-convey logistics instead – how to qualify, which start time to pick, etc. It makes it sound like it’s all about logistics and sleep deprivation.

Don’t be mislead: it’s one of the greatest rides in the world! Here are nine reasons why this unique ride is so appealing:

1. Ride with randonneurs from all over the world

As you settle into the long ride, you’ll find yourself riding with others who ride at a similar pace. During my first PBP in 1999, I rode with randonneurs from Texas, Spain, Italy, France, Bulgaria, England, Australia, and a few other countries. By pure chance, I rode for half a day with an old friend from Toronto (above), and I met another rider from the Bay Area with whom I had corresponded via e-mail.

With more than 5000 riders at the start, you’ll rarely ride alone. Unless you need a break from all the stimulation. Then you can just wave good-bye and speed up or slow down a bit so that the road is yours alone.

2. Be a hero in a festival of cycling

You’ll ride through little villages at 2 a.m., and people will be standing by the roadside, cheering you on with shouts of: “Bravo! Allez, allez!” In many places, locals put up tables with food and water. They cheer as much for the last rider as for the first. They are excited to be part of this event, and they make you feel special. Some riders have said they feel like riding in the Tour de France, but I think it’s even better, because these are local peole, not cycling fans, and their enthusiasm is all the more heartwarming for it.

3. Ride on great roads

Most of the time, PBP goes over the bucolic backroads of Brittany. Cattle graze languidly on green pasture. Hedgerows line the road. Birds chirp in the brushes. The road curves as it dips and rises with the landscape. There is hardly any traffic, and drivers are very considerate. It’s some of the best cycling anywhere.

4. Ride into history

When you ride on those little roads in Normandy, you are riding in the tire tracks of the pioneers of cycling. You can imagine friendly ghosts populating the landscape: Charles Terront, who won the very first edition (top photo); Hubert Opperman (above), the Australian racer who came first in 1931; Juliette Pitard, who completed every PBP over a 30-year period (1921, 1931, 1948, 1951).

If you talk to the spectators, you realize that many of them rode PBP in the post-war years, and are glad to share their memories. Being able to rub shoulders with the greats of our sport is special. Also, don’t skip the awards ceremony! Last time, you were able to meet the three fastest riders in 1961, plus Lyli Herse, Roger Baumann (fastest in 1956 and finisher of 10 PBP), the late Gilbert Bulté (fastest tandem in 1956 and organizer in 1966) and a number of other great anciens.

5. Experience France as it used to be

During PBP, you traverse hundreds of ancient villages that have not changed much in decades, if not centuries. You pass by old churches and canals with beautifully kept lockkeepers’ houses. In the stone villages, there are small bakeries, little brasseries and tiny grocery stores that invite you to stop, eat a meal or refill you supplies.

99% of the time, you ride through a bucolic landscape that is far from the megastores and shopping malls that now infest much of France. If you want to experience France as it used to be, PBP is a great way to do so.

6. It’s relatively affordable

In an age when even short events can cost hundreds of dollars, PBP has remained very affordable. The entry fee is less than $ 200. You pay for your supplies on the road, but it’s hard to spend more than $10 on a meal at one of the controls (above). If you want to sleep, a mattress in one of the gyms in one of the schools that serve as controls costs at most another $10. The rural bakeries you pass rarely charge more than $ 1.20 for a croissant.

So once you’ve taken care of your flight to Paris, PBP is one of the most affordable ways to ride across France.

7. You don’t need to speak French

Touring in France on your own can be daunting at first, especially if you don’t speak French. PBP is geared toward riders from all over the world. The logistics are taken care of. While you should learn a few phrases to show your appreciation to the volunteers, you don’t need a command of French to enjoy this ride to the fullest.

8. You can do it!

Compared to other great adventures, PBP is achievable. It’s not like the Race Across America, which only superhumans finish. It’s not like riding around the world, where you have to quit your job and put your life on hold for a year or two. It’s not like an expensive guided tour, which might wipe out your savings.

PBP is a challenge, but it’s entirely doable. There is a path laid out for you to follow and make this ride a success: The qualifying brevets also act as training, helping you to get in shape for the big ride.

If you are in good shape already, dedicate a cycling season to it, and at the end, in August, you’ll be able to ride 1200 km and have a great time. Even if you take some extra time to visit France – and you should – two weeks will make for one of the most memorable holidays you’ve ever experienced. And as European vacations go, it’s affordable.

9. Feel a great sense of accomplishment

The first time the magnitude of the event hit me was when I traversed the great suspension bridge over the Elorn River in Brest. Before me lay a great harbor of this important port city, bathed in the soft evening light. And I suddenly realized that I had ridden across the length of France. Most of my bike rides are local in nature, but this one, I can trace on a globe!

When I return to Paris at the end of the ride (above), I have completed one of the most incredible rides there is. The sense of accomplishment stays with me for months, if not years.

There are many other reasons to ride PBP. If any of them appeal to you, then your first PBP will be a highlight of your entire life. It’s really that special.

We just signed up our 4000th current subscriber to Bicycle Quarterly. The response to our 50th issue has been overwhelming – both from long-time readers who considered it our “best one yet” and from new subscribers. We received even more feedback than usual, with comments like: “The publication really has come into its own.” and “So finely presented, and I look forward to soaking up all the info and images. Thanks for the high quality of work!”

Thank you to all who have made this possible, by subscribing and by spreading the word about Bicycle Quarterly: telling friends and riding partners, lending copies to someone who is interested, talking about BQ in online forums, and showing BQ to your favorite bike shop and asking them to carry it.

Our printing is paid by subscribers (instead of advertising), so passing the 4,000 mark means we can more print more content in all future issues – maybe not quite as much as our “biggest-ever” 50th issue, but the upcoming Spring 2015 Bicycle Quarterly is getting close!

Bicycle Quarterly provides inspiration and information, and it’s a good read, too. The magazine always has been about new ideas, and the Spring issue goes one step further in that direction: We’ve tested a number of bikes that are quite different from our usual fare. Some are developments of the Allroad bikes we’ve been riding for the last few years, while others provide very intriguing alternatives. (The photos show these bikes, hopefully without giving away too much!)

We researched new ideas that may influence what your next bike looks like. (I know they’ve influenced the bike I just ordered!) And of course, Bicycle Quarterly‘s research always involves amazing rides, wonderful scenery and great adventures.

The Spring issue will be out in March. In the meantime, there still is time to get our “biggest-ever” 50th issue, with one last mailing later this week. So don’t wait to subscribe or renew… And once you’ve finished reading the 108 action-packed pages of the 50th Bicycle Quarterly, the Spring issue one will be on its way!

From time to time, we receive shipments of books that have been damaged. Usually they haven’t been packed well and got damaged in shipping. Sometimes, they have minor flaws that happened during the binding of the book.

Usually, we return these books to the publisher, but when they come from overseas, it’s not worth the hassle (and resources) to send them back. And with our own books, we can’t send them back. Instead, we sell these books at a discount.

If you are a book collector, you’ll probably want a pristine copy. If you are looking for a reading copy, here is your chance to get one at a substantial discount. Your reading experience will be the same – all the pages are there and legible. Here are the titles that are included in the sale:

We have a few 2015 calendars with bumped corners. Once they are on the wall, you will look at the beautiful studio photos of 13 classic bicycles and not notice the minor creases. These are 50% off.

We also have a few copies of the original The Golden Age of Handbuilt Bicycles with bumped corners. The book is currently out of print, but will be re-issued in a smaller format soon. This is your last chance to get the original full-size edition. 20% off.

A few copies of The Competition Bicycle, our technical history of the bicycle seen through the bikes of great champions and amateurs, have suffered a little (creased dust covers, etc.). 20% off.

Some of the Japanese Alex Singerbooks also suffered in shipping. 15% off for bumped corners, 25% off for more serious damage like ripped dust jackets.

We also have a small number of René Herse books that don’t have their clear plastic wraps, and a few others that have slightly bumped corners… 15% off.

To order these books, go to the Bicycle Quarterly bookstore and follow the links to the checkout. In the shopping basket, you will see the damaged copies right below the pristine ones. Supplies are limited – fortunately, we don’t have a lot of damaged copies!

The cycling season has started again. In January and February, the Bicycle Quarterly team begins our training with long rides at an unhurried pace. This year, we’ve been lucky with the weather, with many clear days and gorgeous views. Mount Rainier (above)…

… the Cascade Mountains in the morning mist…

…and Mount Baker near sunset.

Some days have been foggy and wet…

… but with the right clothing and equipment, we enjoy riding, no matter the weather. (We prefer sunshine, though!)

Many of our rides now include some gravel, which provides a nice change of scenery and a freedom from traffic.

We are not in a rush, so there is plenty of time to enjoy the scenery and stop to take photos.

Most of our rides include a stop at a café, bakery or taco truck.

Then we look over our bikes leaning against the wall and are grateful for the wonderful experiences they give us.

Riding when you are “out of shape” sounds uncomfortable and hard, but with friends and bikes like these, the emphasis changes from suffering to experiencing beauty together. As a side benefit, we get in shape for the great adventures of the summer.

The new Compass centerpull brakes have been very well received. Numerous builders have asked for the complete specifications for the brakes, since many riders plan to use them on their new bikes. We sold so many of the centerpull braze-ons that we are currently out of stock of these pivots, but another shipment is expected next week.

We recommend that builder have the brakes on hand when they build the bike, so that they can make sure everything fits just right. We have the specifications available online as part of the instructions for the brakes. This also allows riders to check whether the brakes will fit their existing bikes.

The specifications include detailed drawings that allow builders to get the clearances just right for bikes with 650B x 42 mm tires and full fenders. These measurements are the result of a year’s work: measurements were taken, calculations performed, CAD drawings created, prototypes built… We wanted the entire system of fork/tire/fender/brake/rack to be right, once and for all. These specs will be useful for builders who are not using Compass brakes on their current project, since they show the optimized clearances for tires and fenders.

The Compass CP1 rack is specifically designed to go with the Compass brakes. (The rack only works with centerpull brakes.) The rack is based on a René Herse rack that combines elegance, light weight and rigidity.

It is important that the brake pivots are located at the right height, otherwise the rack will sit too high or too low above the fender. The instructions for the brakes include all measurements a builder needs to build a bike with our brakes and our rack.

The rack and brakes also work for other configurations in addition to 650B wheels and 42 mm tires. For other wheel diameters, the dimensions remain the same in relation to the top of the tire – the builders simply adjusts the measurements for the different outer diameter of the wheel.

It’s been a lot of work to get to this point, but when we rode these brakes during pre-production testing (above), we realized that it was totally worth the effort. The absolute braking power of the Compass brake is great, and the modulation is superb. This gave us great confidence descending challenging mountain roads at speed. As always, the goal is to have more fun on our bikes!

Of all our research on tires, the most revolutionary finding is this: Tire pressure has almost no effect on a tire’s speed. We did not believe it at first, either, so we’ve tested it numerous times. It’s been confirmed numerous times, with different methodologies.

The real revolution is not how you use your pump… What has totally changed our riding are the wide, supple tires, which only work because of this new insight.

First, let’s look at the data. Here is one experiment: We ran three different 25 mm tires (a supple clincher, a supple tubular and a harsher-riding clincher) at pressures from 4.5 and 9 bar (65 and 130 psi). These tests were done on very smooth asphalt (above), a surface where high pressures should offer the greatest advantages. The graphs below show the power required to ride the bike (above) with the tires at a constant speed of 27.8 km/h, but with different tire pressures.

There is no relationship between tire pressure and performance in the tested range. (Lower and higher pressures are unsafe to ride.) The graph above shows some variation in power output (lower is better), but there is no trend. The CX tubular rolls fastest at 5.5 bar, the CX clincher is a little faster at 6 bar, while the Rubino is fastest at 9 bar, but almost as fast at 6.5 bar.

Take-home message: Don’t stress about tire pressure!

This finding has revolutionized our understanding of tires. In the past, we all thought that higher tire pressures made tires roll faster. And that presented a problem for wide tires: A wider tire puts greater loads on the casing than a narrow one. To compensate, you have two choices:

Beef up the casing, which makes the tire less supple and slower.

Lower the pressure, which we thought made the tire slower.

No matter which route you took, then-available science predicted that your wider tire would be slower. It was a catch-22, and for the best performance, you stuck with narrow tires, where you could have a supple casing and high pressure at the same time.

But after realizing that tire pressure doesn’t matter for performance, we were able to explore new possibilities. If lowering the pressure does not make tires slower, you can make supple, wide tires. You run them at lower pressures, and you don’t give up any performance on smooth roads. On rough roads, you gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Instead of a catch-22, you have a win-win-win situation.

It’s this research that has led professional racers to adopt wider tires. They are up to 25 mm now. (Wider ones won’t fit on their bikes!) For the rest of us, there is no reason not to go wider. I now ride 42 mm tires at 3 bar (43 psi), knowing that they roll as fast as a 25 mm tire at 6 bar (85 psi) – or 9 bar (130 psi), for that matter.

To get the most benefit out of these lower pressures, you need supple tires. A stiff sidewall takes more energy to flex, so the tire will be slower. And since the sidewall is stiffer, it also will be less comfortable. You could call it a “lose-lose” situation.

Professional racers have known this all along: As much as their equipment has changed over time, they’ve always ridden supple tires. They usually ride hand-made tubulars (above), but for the rest of us, supple, wide clincher tires now make it possible to enjoy the ride and speed of supple tires on any road.